Aromatic bis cyclic carbonates

ABSTRACT

A composition comprising an aromatic polycarbonate branched or crosslinked with a residue of a compound of the formula   &lt;IMAGE&gt; FIG. I  wherein X, Y, X&#39; and Y&#39; are the same or different and are hydrogen or alkyl of one to about six carbon atoms, inclusive; W, W&#39;, Z and Z&#39; are the same or different and are alkyl of one to about six carbon atoms, inclusive, and E is alkylene or alkylidene of two to about twelve carbon atoms, inclusive.

This is a division of copending application Ser. No. 688,244, filed Jan.2, 1985, now U.S. Pat. No. 4,604,434.

BACKGROUND OF THE INVENTION

Polycarbonates are well known polymers which have good propertyprofiles, particularly with respect to impact resistance, electricalproperties, dimensional rigidity and the like. These polymers aregenerally linear, but can be made with branched sites to enhance theirproperties in specific ways. Low levels of branching are generallyincorporated into the resin by co-polymerizing into the polymer backbonea tri or higher functional reagent to yield a thermoplasticpolycarbonate resin with enhanced rheological properties and meltstrength which make it particularly suitable for such types of polymerprocessing procedures as the blow molding of large, hollow containersand the extrusion of complex profile forms. Special manufacturing runsmust be set aside to prepare these branched polycarbonate resins.

Sufficiently higher levels of branching sites in the resin will causeresin chains actually to join to each other to form partially or fullycrosslinked resin networks which will no longer be thermoplastic innature and which are expected to exhibit enhancements, overcorresponding linear resins, in physical properties and/or in theirresistance to abusive conditions, such as exposure to organic solvents.A wide variety of means have been employed to produce crosslinking inpolycarbonate resin. These generally involve the incorporation of asuitably reactive chemical group either into the resin chain at its timeof manufacture or as an additive to the resin after manufacture, orboth. These reactive groups and the reactions they undergo are generallydissimilar from those characteristic of polycarbonate resin itself andare therefore prone to have detrimental side effects on the physicaland/or chemical properties of the polymer. The conventional test used tojudge the success of these means for crosslinking is to observe theformation of gels due to the crosslinked material when a resin sample ismixed with a solvent, such as methylene chloride, in which normal linearpolycarbonate resin is highly soluble.

A new method has been discovered to prepare branched or crosslinkedpolycarbonate resin. This approach involves the use of an additive tothe resin which has structure and reactivity very similar to that of thepolycarbonate resin repeat unit itself. Thus, it offers the dualadvantages of allowing the branch sites to be incorporated into standardlinear resin subsequent to the manufacture of the resin and of providingthis branching or crosslinking by a method which produces residualstructural groups in the final composition which are expected to bephysically and chemically compatible with the resin.

DESCRIPTION OF THE INVENTION

In accordance with the invention, there is an aromatic polycarbonatecrosslinked with a residue of a compound of the formula ##STR2## whereinX, Y, X' and Y' are the same or different and are hydrogen or alkyl ofone to about six carbon atoms, inclusive; W, W', Z and Z' are the sameor different and are alkyl of one to about six carbon atoms, inclusive,and E is alkylene or alkylidene of two to about twelve carbon atoms,inclusive.

Another aspect of the invention is the compounds of the formula ofFigure I.

A further aspect of the invention is the precursor of the compounds ofFigure I, the compounds of the formula below ##STR3## wherein X, X', Y,Y', W, W', Z, Z' and E are the same as in Figure I.

Alkyl of one to six carbon atoms, includes normal and branched alkyl,i.e. methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl,tert.butyl, neopentyl and 2,3-dimethylbutyl and the like. Normal alkylare preferred. Alkyl of one to three carbon atoms are also preferred.Alkylene of two to twelve carbon atoms, inclusive include normal andbranched such as ethylene, propylene, butylene, isobutylene,2,3-dimethylbutylene, hexylene, dodecylene and the like. Alkylideneinclude isopropylidene, 3,3-decylidene and the like. Alkylene andalkylidene of 2 to 6 carbon atoms are preferred. The phenols of FigureII are readily prepared by a conventional hydrochloric acid/mercaptancatalyzed condensation of an E dialdehyde with an appropriately W and Xsubstituted phenol. Examples of such phenols include the p-cresols,2,4-dimethylphenol and 2-ethyl,4-butylphenol. When only one phenol isused in the reaction, W═Z═W'═Z'═ and X═Y═X'═Y'. When two differentphenol starting materials are used, the substituents will vary dependingon the phenol, per se, the proportions of the specific phenol and therapidity of reaction with the aldehyde. The reaction can be carried outat an elevated temperature, i.e. from about 30° to about 100° C.,preferably 40° to about 60° C. The acid is preferably anhydrous. Themercaptan is present as a catalyst in appropriate quantities.

The bis cyclic carbonates of Figure I are readily prepared from thetetraphenols of Figure II under standard conditions. For example thestandard method of interfacially preparing polycarbonate is alsoapplicable to preparing the bis cyclic carbonates, that is, the use ofaqueous caustic, methylene chloride, phosgene, and triethylamine.Alternatively, the addition of a pyridine/methylene chloride solution ofthe tetraphenol to phosgene in methylene chloride can be employed.Standard work-up conditions such as washing and solvent removal yields asolid from which product is isolated by addition of an appropriatesolvent such as toluene. Product precipitates therefrom. Raising thetemperature to the reflux temperature of the pyridine/methylene chloridesystem improves the yield. When toluene is used as a solvent with areaction temperature of 85° C., the reaction rate is acceleratedsubstantially.

Standard aromatic polycarbonates are crosslinked with the biscycliccarbonates of Figure I through conventional transesterification reactionsystems using transesterification catalysts. Aromatic polycarbonates aremade in the usual manner replete in the literature with the standarddihydric phenols such as bisphenol-A, o,o'o,o'-tetrabromo bisphenol-A,o,o',o,o'-tetra alkyl bisphenol-A and the like. The phrase aromaticpolycarbonate includes aromatic copolyestercarbonate as well, describedin Goldberg U.S. Pat. No. 3,169,121 incorporated by reference.Bisphenol-A polycarbonate is preferred.

The transesterification reaction utilized in the crosslinking iscatalyzed by basic type catalysts usually employed intransesterification reactions, for example, oxides, hydrides, hydroxidesor amides of the alkali or alkaline earth metals as well as basic metaloxides such as zinc oxides, salts of weak acids such as lithium stearateand organotitanium, organoaluminums and organotins such astetraoctyltitanate. Because of potential steric hinderance it ispreferred to use catalyst with less bulky groups, e.g. the lithiumstearate as opposed to the tetraoctyl titanate.

The crosslinking is carried out by reacting the bis cyclic carbonateswith the aromatic polycarbonate in the melt form in the presence ofcatalytic quantities of a transesterification catalyst. One of thebenefits of using a cyclic carbonate is that there should besignificantly less fragments of the polycarbonate chain present. Thecyclic carbonate opens up thus allowing addition at either side of thecarbonate group. This allows formation of structures of the followingtype. ##STR4## wherein X, Y, X' and Y' are the same or different and arehydrogen or alkyl of one to about six carbon atoms, inclusive; W, W', Zand Z' are the same or different and are alkyl of one to about sixcarbon atoms, inclusive, E is alkylene or alkylidene of two to abouttwelve carbon atoms, inclusive; and R, R_(a), R_(b) and R_(c) representpolycarbonates of various chain lengths. The minimum temperature of thereaction is sufficiently high to create a melt of the reactants. Such atemperature is achieved in an extruder or a molding machine such as aninjection or compression molder normally employed for extruding ormolding polycarbonate.

The final physical form of the crosslinked polycarbonate is at leastpartially dependent upon the quantity of bis cyclic carbonate present.If desired gel like forms, usually a high crosslinked thermosetmaterial, can be avoided by utilizing relatively small quantities of thebis cyclic carbonates. The gels occur when greater quantities of thebiscyclic carbonates are present. Also of significance is the reactiontemperature and time.

Below are specific examples of the invention. These examples areintended to exemplify rather than narrow the inventive scope.

EXAMPLE 1 PREPARATION OF TETRAPHENOLS OF FIGURE II A. Preparation of thetetraphenol wherein W═Z═Z'═Z'═methyl and X═Y═X'═Y'═hydrogen.

A 2000 ml four-neck flask was fitted with a mechanical stirrer, a gasinlet tube, a dropping funnel and a drying tube which had a nitrogenpurge line passing past its outlet. The flask was placed in a 50° to 55°C. water bath. To the flask was added 1000 g (9.25 moles) of meltedp-cresol. The flask was purged with nitrogen, then anhydrous hydrogenchloride was introduced until the p-cresol was saturated with it, then 2ml of mercaptoacetic acid was added. With good agitation and continousslow addition of hydrogen chloride, 256 g (1.28 mole) of a 50% aqueoussolution of glutaric dialdehyde was added dropwise over 3 hours. Duringthe addition of the aldehyde, a precipitate began to form and by the endof the addition the reaction mixture had become a thick paste. The waterbath was then removed and the reaction mixture allowed to stand 3 daysat room temperature. Volatiles were then removed with a water aspiratorvacuum and a water layer which had formed on the surface of the mixturewas removed by decanting. Toluene was then added to the flask and themixture stirred until it formed a uniform slurry. The mixture wastransferred to a larger flask where it was mixed with additional tolueneto a final total volume of 4000 ml. The precipitate was collected byvacuum filtration and washed with an additional 1400 ml toluene. Theresulting hard paste was washed twice with 1500 ml water, with a Waringblender being used initially to produce a uniform aqueous slurry. Thefinal pH of the water filtrate was 4 to 5. The sample was dried in avacuum dessicator (about 1 mm) to yield 405 g (65%) of a white powder(mp 220° to 228° C.).

B. Preparation of the tetraphenol wherein W═X═Y═Z═W'═X'═Y'═Z'═methyl. A500 g sample of 25% aqueous glutaric dialdehyde was extracted five timeswith 250 ml portions of methylene chloride and the combined extractsdried over MgSO₄, filtered and the solvent partially removed on a rotaryevaporator to yield 200 ml of a glutaric dialdehyde in methylenechloride solution. By nmr analysis, the solution was found to containapproximately 48 g (0.48 mole) of glutaric dialdehyde.

A 1000 ml four-neck flask was fitted with a mechanical stirrer, a gasinlet tube, a dropping funnel and a drying tube which had a nitrogenpurge line passing past its outlet. The flask was placed in a 60° C.water bath. To the flask was added 489 g (4.0 mole) of2,4-dimethylphenol. The flask was purged with nitrogen, then anhydrousHCl was added until saturation, then 1.0 ml of mercaptoacetic acid wasadded. With good agitation and continuous slow addition of HCl, theglutaric dialdehyde solution was added dropwise over three hours. Aprecipitate began to form after about 130 ml of the solution had beenadded. The reaction mixture was allowed to stand at room temperature for16 hours, then it was slurried in 1200 ml of toluene, vacuum filteredand the precipitate re-slurried in 500 ml toluene, filtered and allowedto air dry. The resultant powder was washed four times with 500 mldistilled water, then two times with 250 ml toluene. The sample wasdried in a vacuum dessicator (about 1 mm) to yield 242 g (91%) of awhite powder (mp 236° to 242° C.).

EXAMPLE 2 PREPARATION OF BIS CYCLIC CARBONATES OF FIGURE I A₁Preparation of the bis cyclic carbonate of the tetraphenol of A above bythe methylene chloride procedure.

A 2000 ml four-neck flask was fitted with a mechanical stirrer, a gasinlet tube, a dry ice condenser which has its outlet connected through adrying tube to a caustic scrubber and an inlet tube about an inch longconnected through polypropylene tubing to a liquid metering pump ("LabPump, Jr.", #RHSY, Fluid Metering, Inc.) to which was connected anaddition funnel. A solution of 74.5 g (0.15 mole) the tetraphenol ofExample 1A and 55 ml (0.68 mole) of pyridine diluted to a total volumeof 300 ml with methylene chloride was placed in the addition funnel.1.25 liters of methylene chloride was placed in the flask. With theflask in a 10° C. water bath, 34 g (0.34 mole) of phosgene was added at1 g/min. The bath was then warmed to 38° to 40° C. and, with vigorousstirring, the solution was added dropwise over a period of 8 hours. Theflask was then allowed to cool to room temperature and the reactionmixture allowed to stand 16 hours, during which time large crystals ofpyridinium hydrochloride formed. The solution was decanted from thecrystals, washed three times with 400 ml distilled water, dried overMgSO₄ and filtered. The solvent was removed on a rotary evaporator toyield a white paste which was placed under a 0.5 mm vacuum for 16 hoursto yield a hard, brittle solid. The solid was broken up and stirred with60 ml toluene to yield a uniform slurry which upon vacuum filtrationyielded a white powder. The powder was washed a second time with 60 mltoluene, then twice with 60 ml methanol, then dried under vacuum toyield 36 g (44%) of a fine white powder (mp 269°-276° C.).

A₂ Preparation of the bis cyclic carbonate of A above by the tolueneprocedure.

The apparatus was set up as described above for the methylene chlorideprocedure. A solution of 74.5 g (0.15 mole) of the tetraphenol ofExample 1A and 55 ml (0.68 mole) pyridine diluted to a total volume of200 ml with methylene chloride was placed in the addition funnel. 1.25 lof toluene was placed in the flask. With the flask in a 10° C. waterbath 5 g of phosgene was added at 1 g/min. The water bath temperaturewas then raised to 85° C. and over a period of 60 minutes with vigorousstirring the solution was added dropwise with simultaneous addition ofphosgene at 0.5 g/min (35 g, 0.35 mole total phosgene). A whiteprecipitate formed in the reaction during the addition. After allowingthe reaction mixture to cool to room temperature and to stand 16 hours,the precipitate, which was a mixture of product and pyridiniumhydrochloride, was collected by vacuum filtration and dried to a whitepowder under vacuum. (Removal of solvent from the filtrate on a rotaryevaporator yields a viscous oil and no additional precipitate). Thepowder was washed twice with 500 ml water, then once with 150 mlmethanol, dried under vacuum to yield 29 g (35%) of a fine, white powder(mp 260° to 277° C.).

B. Preparation of the bis cyclic carbonate of the tetraphenol of Example1B.

A 2000 ml four-neck flask was fitted with a mechanical stirrer, a pHprobe, a gas inlet tube and a Claissen adapter to which was attached adry ice condenser and an aqueous caustic inlet tube. To the flask wasadded 900 ml methylene chloride, 560 ml distilled water, 3.4 mltriethylamine, and a 22 g (0.04 mole ) portion of tetraphenol of Example1B. Phosgene was then introduced into the flask at 1 g/min for 50minutes, with simultaneous addition at 5 minute intervals of additional22 g portions of the tetraphenol (total of 50 g (0.5 mole ) of phosgeneand 220 g (0.4 mole ) of tetraphenol). The pH was maintained at 9 to 11with addition of 25% aq NaOH. The methylene chloride layer was separatedfrom the brine layer, washed once with 350 ml of 3% aqueous HCl, threetimes with 350 ml distilled water, dried over MgSO₄, filtered and thesolvent removed on a rotary evaporator to yield a solid residue. Thesolid was washed twice with 200 ml portions of acetone, thenrecrystallized from toluene to yield 99 g (45%) of a white powder (mp231.5° to 235.5° C.).

EXAMPLE 3 Preparation of crosslinked polycarbonates.

2.5 g (0.01 moles) of bisphenol-A polycarbonate powder (intrinsicviscosity of 0.49-0.52 in methylene chloride at 25° C.) was contactedwith 1.0×10⁻⁵ mole catalyst (0.1 mole %) and 2 mole % or 5 mole % biscyclic carbonate at 300° C. under N₂ for a period of twenty minutes withthorough stirring of the melt. The results are shown below. In additionto these samples, five separate controls were run at the same time andtemperature--polycarbonate alone, polycarbonate plus tetraoctyl titanate(TOT), polycarbonate plus lithium stearate (LiST), polycarbonate plusExample 2A bis cyclic carbonate, and polycarbonate plus Example 2B biscyclic carbonate. No gels, as positively observed in the Table belowwere formed with any of the control formulations.

                  TABLE 1                                                         ______________________________________                                        BIS CYCLIC CARBONATE   % GEL*                                                 Example   Quantity, mole % TOT    LiST                                        ______________________________________                                        2A        2                23     25                                          2A        5                57     47                                          2B        2                 5     25                                          2B        5                 4     52                                          ______________________________________                                         *Quanity of gels was determined by swelling the resin "blobs" produced in     methylene chloride, filtering and washing with additional methylene           chloride.                                                                

What is claimed is:
 1. A bis cyclic carbonate of the formula ##STR5## wherein X, Y, X' and Y' are the same or different and are hydrogen or alkyl of one to about six carbon atoms, inclusive; W, W', Z and Z' are the same or different and are alkyl of one to about six carbon atoms, inclusive, and E is alkylene of two to about twelve carbon atoms, inclusive.
 2. The carbonate of claim 1 wherein W═Z═W'═Z'═methyl and X═Y═X'═Y'═hydrogen.
 3. The carbonate of claim 1 wherein W═X═Y═Z═W'═X'═Y'═Z'═methyl.
 4. The carbonate of claim 1 wherein E is alkylene of 2 to 6 carbon atoms.
 5. The carbonate of claim 4 wherein E is normal alkylene of three carbon atoms.
 6. The carbonate of claim 2 wherein E is normal alkylene of three carbon atoms.
 7. The carbonate of claim 3 wherein E is normal alkylene of three carbon atoms. 